.container {
    background-color: aqua;
    width: 1200px;
    margin: 0px auto;

    $height: 200px;

    .left {
        width: 300px / 500px * 100%;
        background-color: #00ff00;
        height: $height;
    }

    .right {
        width: 150px / 500px * 100%;
        background-color: #ff0000;
        height: $height;
    }
}
